prime of life

Tree-of-Life

The Tree-of-Life is a fictional plant (the ancestor of yams, with similar appearance and taste) in Larry Niven's Known Space universe, for which all Hominids have an in-built genetic craving. Consumption of Tree-of-Life makes human-related species turn into Pak Protectors, as a result of a symbioticvirus that grows in the root; however, the virus requires enough Thallium to develop, which is why it failed to grow on Earth. To those too young to develop into Protectors, Tree of Life smells repugnant, while the virus is fatal to those too old.